In the field of wireless communications technologies, spectrum resources are limited, and how to improve the utilization rate of spectrum resources is particularly important. In a multiple-antenna technology, a transmit signal and a receive signal in a space domain are processed to improve the utilization rate of spectrum resources. In the multiple-antenna technology, multiple antennas at a transmit end may concurrently send multiple signals in a same frequency, so as to make full use of a space resource to improve a system capacity in a case in which the spectrum resources are not increased.
In the multiple-antenna technology, a freedom degree of a transmit-end channel visible on an air interface depends on a quantity of logical channels of frequency division, the quantity of logical channels may be considered as a quantity of antenna ports, a quantity of physical antennas is greater than or equal to the quantity of antenna ports, and mapping of a physical antenna to an antenna port (also called antenna port mapping) is one of the key technologies to implement the multiple-antenna technology.
At present, in an antenna port mapping process, in order to ensure isolation and coherency, a co-polarized antenna array is generally mapped to only one same antenna port. An array antenna formed by cross-polarized elements is used as an example. Because an antenna has two polarization directions, mapping to only two antenna ports is supported at present. As a receiving capability increases at a receive end, a requirement for mapping to more than two antenna ports is ever-increasing. Therefore, how to implement mapping of a physical antenna to more than two antenna ports is particularly important.